Breve notícia sôbre a espermatogênese de Lutosa brasiliensis Brunner (Tettigoniodea-Stenopelmatidae)

Lutosa brasiliensis, an Orthopteran Tettigonioidean belonging to the family Stenopelmatidae is referred to in this paper The spermatogonia are provided with 15 chromosomes, that is, 7 pairs of autosomes and a single sex chromosome. One pair of autosomes is much larger than the rest, two pairs are of median sized elements, and four pairs are of small ones. The daughter sex chromosomes show at anaphase great difficulty in reaching the poles, being left for a long while in the region of the equator where they are seen stretched one after the other on the same line or lying side by side in different positions. When the spermatogonium divides each daughter cell gets passively its sex chromosome. Though slowly, the sex chromosome finishes by beins enclosed in the nucleus. Its behavior may be attributed to a very weak kinetic activity of the centromere. In view of se pronouced an inertness of the sex chromosomes, two things may be expected : primary spermatocyte nuclei with two sex chromosomes, and primary spermatocytes with the sex chromosome lying outside the nucleus. Both situations have been discovered. The latter, together with the delay of the spermatogonial sex chromosome in reaching the poles suggested to the anther the mechanism which might have given origin to the cases in which the sex chromosome normally does not enter the nucleus to rejoin the autosomes, remaning outside in its own nucleus. It may well be supposed that accidents like that found in the present individual have turned to be a normal event in the course of the evolution of some species. Trie primary spermatocytes are provided with chromatoid bodies which remain visible all over the whole history of the cells and pass to one of the resulting secondary spermatocytes, the larger of them being found later in the area occupied by the tails of the spermatozoa. No relation of these bodies to nucleoli con?d be established. Pachytene and diplotene nuclei are normal Metaphase nuclei show 7 autosomal tetrads, one of which being much larger than the rest. At this stage the chromosomes have a pronounced tendency to form clumps. Even when they are separated from each other they generally appear competed by chromosomal substance. The sex chromosome Hes always in one of the poles, being enclosed in the nucleus formed there. The stickness of the chromosomes can also be noted at anaphase. Telophase chromosomes distend them- selves for giving origin to secondary spermatocyte nuclei in a state comparable to a beginning prophase. As the secondary spermatocytes approach metaphase the autosomes appear entirely divided except at the kinetochore where the chromatids remain united. In the division of the secondary spermatocytes nothing else merits special reference.

Organization of the cysts in bee (Hymenoptera, Apidae) testis: number of spermatozoa per cyst

The morphology of the cyst cells in Apis mellifera Linné, 1758, Scaptotrigona postica Latreille, 1804, and Melipona bicolor bicolor Lepeletier, 1836 testis, as well as the average number of spermatic cells are reported. The data indicates a supporting and nourrishing role of the cyst cells to the developing cystocytes. The counts of immature spermatozoa in the cysts show an average of 202.8 ± 21.2 spermatozoa for A. mellifera, 117.4 ± 8.68 for S. postica and 88.8 ± 15.57 for M. bicolor, which predict the occurrence of 8 mitotic cycles in the cystocytes of A. mellifera and 7 in the meliponines, considering that only one spermatozoom originates of each final spermatogonium.

Análise citológica e cariométrica da ação da colchina sôbre a espermatogênese dos hemípteros

The action of colchicine upon the spermatogenesis of Triatoma infestans, (Hemipt. Heteroptera), has been studied and the different categories of giant spermatids that appear during the treatment have been compared with the nuclear volumes of the whole series of normal spermatogenetic stages. The following facts have been ascertained: 1) 4 hours after the treatment the gonial mitotic metaphases, and the 1st. and 2nd. metaphases of meiosis are stopped. The prophasic stages of meiosis and diakynesis appear to be normal. After 9 days of treatment, all the tetrads are broken in the meiotic metaphases and the cells appear with 44 and 22 chromosomes respectively, scattered in the cytoplasm. 2) At 9 days, practically all spermatogenetic stages have disappeared except for a few cysts of spermatogonia, and practically the whole testicle is full of cysts of spermatozoa and spermatid, with some large zones of necrosis with pycnotic nuclei. The spermatids appear to be of different sizes and the statistical analysis of the nuclear volumes gives a polymodal hystogram with 4 modes, whose volumes are in the ratio of 1:2:4:8. Ripe spermatozoa seem to have a certain volume variability, that has not been possible to analyse quantitatively. All these facts confirm what DOOLEY found in the colchicinized Orthoptera testicle. 3) The caryometric analysis conducted statistically on the normal stages of the spermatogenesis (resting spermatogonia, gonial prophases, leptotene, "confused stage", diakynesis, and spermatid) revealed the following facts: a) Considering the volume of the resting, spermatogonia as 1, their mitotic prophases have a volume of 2. Some rare prophases appear to have a volume of 4 and probably belong to tetraployd spermatogonia normally present in the testicle of Hemiptera. b) The first spermatocyte at the beginning of the auxocitary growth (leptotene) has a volume of 2, which is equal to that of them gonial prophase. It grows further during the "confused stage" and reduplicates, reaching thus the volume of 4. Diakynesis has a rather variable nuclear volume and it is higher than volume 4. This is probably of physico-chemical nature and not a growth increase. c) The spermatid at the beginning of the spermiogenetic process has a volume of 1 which is very constant and homogeneous. 4) These results can be summarized concluding that the meiotic process begins from a spermatogonium at the end of his mitotic interphasic growth (vol. 2) and instead of entering into the mitotic prophase transforms itself into the leptotene spermatocyte. During the diplotene ("confused stage") the volume of the nucleus doubles once more and reaches volume 4. In consequence of the two successive meiotic divisions the spermatid, although having an haploid number of chromosomes, has a nuclear volume of 1, just like the diploid spermatogonium. The interpretation of this strange result probably comes from the existence of the "tertiary split" in the chromosomes of the haploid set, that has been illustrated in the Hemiptera by HUGUES SCHRADER and in Orthoptera by MICKEY and co-workers. The tertiary split indicates that the chromosomes of the haploid set are constituted from almost two chromonemata, and this double constitution corresponds to the double cycle of reduplication that takes place during the spermatogenesis starting from the resting gonia. In Triatoma infestans the tertiary split appears in the chromosomes in the 1st. and 2nd. metaphases and in the diakynesis. In the blocked metaphases at the 9th. day of colchicinization some of the 44 elements scattered in the cytoplasm, show, when properly oriented, the split very clearly. Some new and strange facts revealed by SCHRADER and LEUCHTEMBERGER in Arvelius suggest the possibility of other interpretations of the rhythmic growth in special cases. There appears the necessity of more knowledge about the multiple or simple constitution of the chromosomes in somatic and spermatogonial mitosis.